SPARK PLUG ?

Thu Nov 15, 2012 1:14 pm

I see there are four different types (1) 18 Y light service Champion (2) 15 Y moderate service Champion (3) 18R52 moderate service Prestolite (4) 6 heavy service Champion I got these from parts catalog TC-37F what would be the best choice for Old Nellie 1948 ser# 34846 J4 magneto. Thanks Johnny J

Re: SPARK PLUG ?

Thu Nov 15, 2012 1:25 pm

In regards to Champion brand plugs, the higher the model number on the plug, the hotter the plug.

Re: SPARK PLUG ?

Thu Nov 15, 2012 1:28 pm

Johnny, the following is from the Cub FAQ page located here cubfaq.php

Everybody has their favorite brand. Many lean towards Champions but that is up to your preference. For show, or light use you should go for a something in the heat range of a Champion D21. If you plan to really put your Cub to work then a Champion D15 or D16 would be better.

Re: SPARK PLUG ?

Thu Nov 15, 2012 2:49 pm

I use my Cub a fair amount. Tried the D-16's found them way too cold a plug. Went to Champion D-21's a number of years ago, won't use anything else. I tried the Autolite and the NGK's -- went back to the D-21's. Like oil it is personal preference, but for me summer, winter, spring and fall D-21's are the right plug.

Re: SPARK PLUG ?

Thu Nov 15, 2012 3:36 pm

What are the visible effects of using a spark plug that is too cool or too hot?

Re: SPARK PLUG ?

Thu Nov 15, 2012 6:15 pm

Stanton wrote:What are the visible effects of using a spark plug that is too cool or too hot?

If the plugs run too cool, you normally see excessive carbon buildup and subpar engine performance, if too hot, the engine can run hotter, you have to find a happy medium.

I have always used AC Delco C87 plugs, just my personal preference.

Re: SPARK PLUG ?

Thu Nov 15, 2012 6:34 pm

Stanton wrote:What are the visible effects of using a spark plug that is too cool or too hot?